Liquid chromatography coupled to high resolution (tandem) MS has emerged as a mature technique for the structure elucidation of emerging toxicants in environmental samples. A major challenge in the identification workflow is the assignment of a chemical structure to the molecular formula derived from accurate mass measurements and isotope patterns. Compound database searching � for example in ChemSpider or PubChem � often reveals tens to thousands of possible candidate structures for an unknown compound. Thus, thorough selection strategies are required to narrow down the number of candidates, which are finally chosen for confirmation by reference standards. We present a systematic strategy comparing predicted properties of the candidates with those derived from different steps of the analytical procedure. These include among others a comparison of predicted and measured retention behavior in LC, comparison of ionization behavior in positive and negative ion mode electrospray and atmospheric-pressure chemical ionization, and predicted and measured MS fragmentation.

Structure elucidation strategies for unknown emerging toxicants based on liquid chromatography-high resolution mass spectrometry

243rd National Meeting (2012)

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